Method of manufacturing sheet metal.



PAT NTED Nov. 5, 1907.-

A. RIDD. METHOD OFIMANUFAGTURING SHEET METAL.

APPLICATION FILED SEPT. 29. 19-05.

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AMBROSE RIDD, OF NEWPORT, KENTUCKY.

METHOD OF MANUFACTURING SHEET METAL.

Specification of Letters Patent.

Patented Nov. 5, 1907.

Application filed Se t b 29. 1905- Serial No, 280,707.

To all whom it may concern:

Be it known that I, Animosn R1131), a citizen of the United States,residing at Newport, in the county of Campbell and State of Kentucky,have invented a new and useful Method of Manufacturing Sheet Metal, ofwhich the following is a specification This invention relates to themanufacture of sheet metal, and particularly to the manufacture of blacksheets to be used in the production of planished iron or Russian iron.

One of the principal objects of the invention is to preserve thedelicate film of oxid which forms on the sheets during the severaloperations in reducing the metal from the form of bars to sheets, theseoxid films being afterwards densified in the formation of the enamellike surface characteristic of Russian sheet iron and other planishedsheets.

A further object of the invention is to preserve the flexibility of thefilm of oxid and prevent flexing by maintaining the metal at all timesat a temperature sufficiently high to avoid checking or chilling of thesheet and consequent injury to the film of oxid.

A still further object of the invention is to provide an improved methodof manufacturing sheet metal which consists in rolling a pack of sheetsat a high temperature, stripping the sheets apart while still hot in thepresence of an oxidizing agent, thereby oxidizing the surfaces and thendensifying the oxidized surface by pressure without permitting thesheets to cool below a dark cherry red heat.

In the manufacture of black sheets as ordinarily practiced, the metal inthe form of a bar is heated and then passed through the rough rolls andthen through the chilled rolls until the sheets are reduced to asufficient extent. The sheets are then matched; that is to say,assembled in packs of two, three, four or more, and again passed throughthe rolls until they are of the required gage. During these operationsno particular care is taken to preserve the sheets at a hightemperature, and in following the ordinary method the sheets are allowedto cool to a considerable extent, especially during the matchingoperation and after the last pass where the pack of sheets is allowed tocool. After the cooling operation, the edges of the pack are trimmed byshears and then the sheets are stripped or separated from each other.The sheets'resulting from this ordinary method of rolling are known asblack sheets and are sometimes used in the manufacture of Russian iron.This metal, Russian iron, is a sheet of iron or steel, both surfaces ofwhich have an enamel-like finish that is formed by condensing andplanishing the film of oxid deposited on the surface of the sheet eithernaturally or artificially. The sheets are then separated from each otherwhen cold or nearly so, and it is found that in practically all casesthe oxid between the sheets will be broken and displaced, portions ofthe films of oxid clinging in spots to one sheet, while other portionscling to an adjacent sheet, so that each separate sheet will haveportions of its surface covered with oxid, and other portions uncoated.This condition of the sheets, however, is not objectionable where it isnot essential to retain the film of oxid, the sheets for some purposesbeing placed in a pickling bath in order to remove all trace of the oxidand then coated with tin, zinc or other metal. In the manufacture ofRussian iron, however, it is essential that the sheets be provided withperfectly smooth layers or films of oxid of uniform thickness, and ifthe ordinary sheet manufactured as above described is to be used for themanufacture of Russian sheet iron, the surface of the sheet must bereoxidized, and in such case the film of oxid at one point may be muchheavier and thicker than the film at another point, so that insubsequent treatment, the degree of condensation of the oxid will differat different points throughout the sheet. In carrying out the presentinvention the utmost care is taken to preserve the integrity of the filmof oxid, and in the process to so separate the sheets that the filmbelonging to each sheet will cling to that sheet alone.

The accompanying drawing is a diagram illustrating apparatus forcarrying the invention into effect.

In starting the operation, the bar or ingot is thoroughly cleaned by achemical or mechanical process or both. The bar or pairs of bars arethen heated in a suitable furnace, or in an annealing oven A, and duringthe heating process there must be no visible lifting of the scale on thesurface of the bar or bars. The bar is then taken from the furnace andthe oxidizing process begins, owing to the exposure of the metal to theair, which acts as the oxidizing agent. The bar or pair of bars are thentaken to the roughing rolls B which are maintained at a hightemperature, and given one or two passes. From the roughing rolls thebars are taken to what is termed the chill rolls 0. Said rolls must,also, be maintained at as high a temperature as will admit of successfullubrication of the journals of the rolls, the temperature being from sixhundred to eight hundred degrees Fahrenheit,- and higher if possible.The sheets are reduced in pairs in the usual way on these rolls to aboutsixteen or eighteen gage, this operation occupying about one minute oftime.

The rolls are maintained at as high a temperature as possible in orderto preserve and densify the film of oxid on the surface of the sheet,and said rolls are geared together, so that both will rotate at uniformspeeds in order to avoid any lagging of one or other of the rolls andconsequent injury to the film of oxid, the sheets being subjected to nostress except the actual compression during the rolling process. Duringthis rolling process the hot rolls act upon the oxid coated surfaces ofthe sheets and compress them, and the sheets have been exposed to theair for about one minute.

The thin sheets after being reduced in pairs are stripped apart while ata dark cherry red heat and instantly placed without cooling into anannealing oven or softening furnace D, so arranged that the heatingflame will not come into direct contact with the sheets, and theoxidizing process virtually stops the moment the pack enters thefurnace. The stripping of the sheets while still hot is of theutmostimportance, for the reason that if the sheets are allowed to cool beforestripping, the film of oxid will not only be injured by the reduction oftemperature but will tend to cling partly to one sheet, and partly tothe adjacent sheet. If the sheets are separated while hot, however, eachfilm will cling to the sheet to which it was initially formed, and thetwo films will separate from each other.

In the ordinary process, as before pointed out, the sheets which havebeen rolled in pairs or packs, are allowed to cool or partly cool beforestripping, and then are allowed to lie on the mill standing or floor,and while cold, or at a comparatively low temperature are matched. Thismatching process consists in placing three, four, or more sheets in apack, and the pack is subsequently passed through the rolls. In carryingout the present invention, however, the sheets are not allowed to cool.They are stripped while still at a high temperature in the presence ofan oxidizing agent, that is to say, in the open air, and instantlytransferred to the annealing or other heating oven in order that suchtemperature may be maintained. The sheets are then matched in threes orfours in the usual manner, except that the matching takes place in theannealing oven instead of on the mill standing. The pack of sheets isnow ready to be run over; that is to say,

passed through the hot rolls 0 once or twice, and then the pack, stillat a dark cherry red heat, is ready for the next steps. In front of therolls is arranged a hot table E which, in the present instance, isformed of a box or casing of wrought or cast iron, the casing inclos inga combustion chamber which may be supplied with any suitable fuel inorder to maintain the table at a high temperature, preferably at a darkcherry red. The pack is placed on this table in order to conserve theheat.

At a point adjacent to the table is a shearing machine F of any ordinaryconstruction.

In carrying out the present invention, the pack of sheets is receivedfrom the rolls at approximately a cherry red heat, is placed on thetable E, and immediately trimmed by the shears F, and the sheets arethen separated while still hot in the open air, which acts as anoxidizing agent, and it is found that when separating in this manner thefilms of oxid Will split evenly, each film being retained by the sheeton which it was originally formed, and the sheets being thus in perfectcondition for the subsequent densifying and planishing process employedin the manufacture of Russian sheet iron. As soon as the sheets areseparated from the pack they are at once, before cooling, placed in anannealing oven G, and after being subjected to an annealing operationare in condition for the further steps of the process, there being inpractice from thirty to forty sheets in oven G before the next step isproceeded with. At this stage of the operation the further steps may becarried on in accordance with my method patent, issued August 8, 1905,No. 796,452, the sheets being passed through highly burnished finishingrolls H in the manner described in said patent. There is little if anyoxidation going on while the sheets are being planished and burnished,as they are not brought into contact with the atmosphere, it beingpreferred to pass the pack from the rolls to a heating chamber at oneside of the mill stand, and then back across to a heating chamber at theopposite side, if necessary.

In. manufacturing the sheets in the manner described, considerableexpense is saved in the production of sheets for the manufacture ofRussian sheet iron, and the product is more uniform and of greatercommercial value than where the usual reoxidizing processes must becarried into effect, the varying thickness of the film of oxid in thelatter case being such as to impair the strength of the metal andprevent the production of an enamel-like surface of uniform resistingqualities in appearance.

I claim:-

1. The method of manufacturing sheet metal, which consists in rolling apack of sheets at a high temperature, stripping the sheets apart whilestill hot in the presence of oxidizing agents, thereby oxidizing thesurfaces, and then densifying the oxidized surface by pressure withoutpermitting the sheets to cool below a dark cherry red heat.

2. The method of manufacturing sheet metal which consists in rolling apack of oxid coated sheets at a high temperature, stripping the sheetsapart while still hot to separate the films of oxid from each other andpreserve on each sheet the film of oxid initially formed thereon, thestripping operation being accomplished in the presence of an oxidizingagent, thereby further oxidizing the surfaces, and then densifying theoxid surfaces by pressure. In testimony that I claim the foregoing as myown, I have hereto affixed my signature in the presence of twowitnesses.

AMBROSE RIDD. Witnesses H. L. I'IAW'KINS, .TNo. C. Dnsross.

